Elevated cortisol in patients with type 2 diabetes mellitus and comorbid depressive symptoms is associated with poor glycemic control and reduced insulin levels

BACKGROUND: Diabetes and depression are highly prevalent chronic conditions, and their comorbidity further impacts quality of life and disease outcomes. Cortisol, the primary stress hormone and a diabetogenic hormone, plays a potential role in linking these conditions. Chronic stress may lead to persistently elevated cortisol levels, which may influence metabolic activity and glycemic control. This study aimed to determine the prevalence and severity of depressive symptoms among patients with type 2 diabetes and to evaluate the association of cortisol levels with depressive symptom severity and glycemic control. METHODS: In this case-control study, we recruited 100 individuals without diabetes and 200 diagnosed patients with type 2 diabetes. Participants were screened for clinically significant depressive and anxiety symptoms using the Hamilton Depression Rating Scale (HAM-D) and Hamilton Anxiety Rating Scale (HAM-A), respectively. Morning cortisol levels were measured, and their associations with depressive symptom severity and glycemic control were evaluated in patients with type 2 diabetes. RESULTS: The prevalence of clinically significant depressive symptoms was higher in patients with type 2 diabetes compared to individuals without diabetes (38% vs. 13%, p < 0.001). Similarly, clinically significant anxiety symptoms were more frequent in patients with type 2 diabetes (14.5% vs. 9%, p = 0.03). Mean cortisol levels were significantly higher in patients with type 2 diabetes (p < 0.001). Among patients with type 2 diabetes, those with severe depressive symptoms had higher cortisol and HbA1c levels and lower insulin levels (p < 0.05). Longer diabetes duration and exclusive insulin therapy were associated with less favorable metabolic profiles. Independent predictors of hypercortisolism included moderate-to-severe depressive symptoms, elevated HbA1c, longer disease duration, insulin therapy, and diabetic complications. CONCLUSION: In patients with type 2 diabetes and comorbid depressive symptoms, higher cortisol levels were associated with poorer glycemic control and lower insulin levels, particularly in those with severe depressive symptoms. These findings support the importance of incorporating mental health screening into diabetes care for better disease management.